1. Field of the Invention
This invention relates to roofing shingle trimming tools, and more particularly to tools for patterning laminated asphalt roofing shingles.
2. Description of Related Art
For many years, standard asphalt shingles were made from a single layer. Such standard asphalt shingles are normally patterned by cutting them with a standard utility knife which is a manual (hand-held) tool. Standard asphalt shingles can be cut relatively easily by making a single score (cut) into the back side of the shingles, with the blade extending through the shingles from back to front. They are cut from the backside, because the front side is coated with abrasive material which rapidly dulls utility knife edges.
Contemporary laminated roofing shingles are quite popular in the contemporary market for roofing shingles. The laminated roofing shingles are constructed from a pair of layers of material, which when scored (cut) with a standard utility knife or any other commercially available knife requires multiple scores (usually three or four scores) that quickly dull the knife point of the utility knife or other types of commercially available knives. The reason for quickly dulling the knife point is that one must cut through one layer of granular asphalt before scoring the back of the second layer.
The temperature conditions during cutting shingles outdoors vary from extremely cold to very hot temperatures. As the ambient temperature changes, the properties of the shingles change from being very hard and nearly impossible to cut with a utility knife to being very soft at high temperatures and relatively easy to cut with a utility knife. In the case of laminated shingles these highly variable environmental conditions result in exaggeration of the temperature effect, but even hot and soft laminated shingles still require a good deal of effort to score the shingles.
U.S. Pat. No. 1,814,151 of Gundlach for a "Shingle Cutter" describes a stationary lower knife blade provided with a beveled cutting edge. There is an upper blade which is secured for vertical swinging movement towards and away from the stationary lower knife blade. The upper blade has a longitudinal V-shaped cutting edge disposed in vertical alignment with the cutting edge of the stationary lower knife blade. The upper blade is secured to the body of the tool at a pivot point at one end of both the upper blade; and the lower blade is secured for rotation of the upper blade towards and away from the lower blade. A lever is secured to the distal end of the upper blade and the support of the lower blade.
U.S. Pat. No. 326,916 of Morse dated Sep. 22, 1885 for a "Paper Cutting Machine" a machine for cutting paper with a movable knife secured to a cutter-bar hinged to brackets by a pair of pitmen. When the cutter-bar is actuated a draw cut is provided. There is no description of anything below the paper being cut other than a table so it appears that the knife cuts the paper without any interaction with a lower blade.
U.S. Pat. No. 600,856 of Brinkman issued in 1898 for a "Tile Cutting Machine" shows an arrangement for cutting tiles, presumably rigid ceramic tiles, in which an upper blade with serrated teeth is secured for vertical motion down towards a lower blade with serrated teeth which "wedge into and divide the tile without chipping or breaking . . ." the tile.
U.S. Pat. No. 1,805,163 of Buckner issued in 1935 for a "Belt Cutter" shows an anvil plate with a V-shaped groove. The cutter blade has a matching V-shape cross-section which appears to match and fit into the V-shaped groove. A camming action of cam abutments 16 and stops 28 drive the blade laterally when it reaches proximity to the anvil plate. The text is silent on the blade shape, stating that "the co-acting bevelled surfaces between the parts 16 and 28 allow the blade to feed itself nicely and smoothly in the groove of the anvil plate 10." Thus the cutter blade severs the work placed over the anvil plate with a sliding action, without the cooperation of a lower blade.